AW55-50SN Pump, remanufactured and ready to install. Fits the AW55-50SN. Ships fast from the USA.
If your Volvo S60, V70, XC90 or S80, Saab 9-3 or 9-5, or Saturn Ion with the Aisin five-speed engages late, slips under throttle once hot, or has started leaking at the bell housing, the front pump is one of the first assemblies to check. This listing is a complete AW55-50SN / AW55-51SN pump assembly with the stator support, pump plate and gear set, and it comes with the two brake piston assemblies that live behind it. It is a good fit for a rebuilder who has a damaged pump body, a scored gear pocket or a broken stator support and wants a matched assembly rather than loose pieces.
The AW55-50SN uses a gear-type front pump turned directly by the torque converter hub. Every pound of pressure in the unit starts here: the regulator valves in the valve body turn pump output into line pressure, converter feed and lube, and the linear solenoids then trim it for each shift. Because this transaxle relies on solenoid-controlled pressure for every clutch and brake apply, a pump that has lost volume does not cause one bad shift; it makes the whole unit soft and slow, and the TCM chases the problem with adaptive corrections it cannot finish.
On this assembly the stator support also carries the B1 and B2 brake pistons. The listing includes the B2 piston with its 12-spring return assembly, four frictions, four steels, a stepped .150 in. pressure plate and snap ring, plus the B1 piston (casting B1-3) with a 15-spring return, two frictions, two steels and a .138 in. pressure plate.
Keep the failure pattern in mind. GearBoxList notes that on high-mileage units, wear debris from the converter clutch tends to clog the valve body first, and the pump bushing then wears out and leaks. A unit with harsh shifts and solenoid performance codes is usually a valve body job; a unit that is soft everywhere is more likely the pump.
Check the fluid level hot and look at the fluid for burnt smell and metal. Then put a gauge on the line pressure port and compare idle and stall readings to the spec for your vehicle. Low pressure in every range points to the supply side, but rule out the pressure regulator first: Sonnax warns that worn regulator and modulator bores in the AW55 valve body leak pressure in a way that looks a lot like a weak pump. Our AW55-50SN service guide lays out that valve body inspection, and converter hub and pump bushing wear explains how to read the hub and bushing once the pump is out.
This pump assembly is listed for the AW55-50SN and AW55-51SN. GM versions are called AF23 and AF33, and the family was used by Volvo, Saab, Opel, Saturn, Nissan, Renault and others from about 1999 on. Internal details changed over that run, so match the hard specs before you buy:
If your old pump measures differently, or you are not sure, send us your year and VIN and we will check it. Other parts for this family are in the Aisin transmission collection, and a year-specific 2000-up AW55-50SN pump is also listed.
| Fits | AW55-50SN |
| Part type | Pump |
| Condition | Remanufactured |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
It is listed for both the AW55-50SN and AW55-51SN, which GM calls AF23 and AF33. Match the stator support casting 906D-10A, the .846 in. bushing ID and the 2.750 in. stator shaft length to your old pump, or send us your year and VIN to check.
No. The seals, O-rings, lip seals and sealing rings are the original ones. Treat the assembly as a core-ready part and reseal it with new parts from a rebuild kit before installing it.
The pump plate, gear set and stator support, plus the B2 brake piston assembly with 4 frictions and 4 steels and the B1 brake piston assembly with 2 frictions and 2 steels, each with its return springs, pressure plate and snap ring.
A worn valve body usually gives harsh or erratic shifts and solenoid codes. A weak pump gives low pressure in every range, slow engagement and soft shifts everywhere. Test line pressure, and inspect the regulator bore before condemning the pump.
Use what the vehicle label calls for. Most Volvo and Saab applications are filled with JWS 3309 type fluid. GearBoxList lists 7.2 liters total capacity, so a pan drain only changes part of it.
Yes. Reset the transmission adaptations with a scan tool after the rebuild and drive the vehicle through all gears so the TCM can relearn clutch fill times.
